成年追赶生长大鼠内脏脂肪堆积与神经肽Y的关系研究

Study on the relationship between visceral fat accumulation and neuropeptide Y in adult catch-up growing rats

目的:观察热卡限制导致的成年期追赶生长大鼠躯干脂肪堆积与内脏脂肪组织神经肽Y(NPY)表达的关系。方法:40只8周龄雄性SD大鼠随机分为正常饮食(NC4/NC12)组、限制饮食(R4)组、追赶生长(RN/RH)组。实验第4周、第12周检测大鼠体重、双能X线吸收测量法检测躯干脂肪含量、躯干与全身的脂肪比例,Western blot测定大鼠附睾脂肪组织NPY蛋白表达,实时荧光定量聚合酶链反应(qPCR)方法测定大鼠NPY mRNA表达,同时苏木精-伊红(HE)染色检测附睾脂肪细胞形态学变化。结果:与NC4组比较,热卡限制使R4组大鼠体重、附睾脂肪细胞直径明显下降(P<0.01),附睾脂肪组织NPY mRNA及蛋白表达显著升高(P<0.01);但躯干脂肪含量及躯干与全身脂肪比例无明显变化(P>0.05)。经开放饮食追赶生长8周后,与NC12组比较,RN及RH组大鼠体重尚未完全追赶(P<0.05),但躯干脂肪含量、躯干与全身脂肪比例、附睾脂肪组织NPY表达和直径显著升高(P<0.01),其中以RH组改变最为著;相关分析结果显示,附睾脂肪组织NPY mRNA表达的改变与躯干脂肪含量、躯干与全身脂肪比例呈正相关关系(r=0.625,0.533,P<0.01)。结论:NPY在热卡限制导致的成年期追赶生长大鼠内脏脂肪中表达显著增加,介导了该模型躯干脂肪含量、躯干与全身脂肪比例增加的追赶肥的发生。

Objective:To observe the relationship between the body fat accumulation and the expression of neuropeptide Y(NPY)in visceral adipose tissue among adult catch-up growing rats caused by calorie restriction.Methods:Forty 8-week-old male SD rats were randomly divided into normal diet group(NC4/NC12),restricted diet group(R4)and catch-up growing group(RN/RH).The body weight of rats was measured at the 4th and 12th week of the experiment.The trunk fat content and the ratio of trunk to whole body fat were measured by dual energy X-ray absorptiometry(DEXA).The expression of NPY protein in rat epididymal adipose tissue was measured by Western blot.The expression of NPY mRNA was detected by qPCR.At the same time,the cell morphology changes of epididymal adipocytes were detected by HE staining.Results:Compared with NC4 group,caloric restriction significantly decreased body weight and epididymal adipocyte diameter of rats in R4 group(P<0.01),whilethe NPY mRNA and protein expression were significantly increased in epididymal adipose tissue(P<0.01).However,there was no significant change in trunk fat content and trunk/whole body fat ratio(P>0.05).After 8 weeks of catch-up growing with open diet,compared with NC12 group,the body weight of rats in RN and RH groups were not completely caught up(P<0.05),but the trunk fat content,trunk/whole body fat ratio,NPY expression and diameter of epididymis adipose tissue were significantly increased(P<0.01),especially in RH group The results of correlation analysis showed that the change of NPY mRNA expression in epididymal adipose tissue was positively correlated with trunk fat content and the ratio of trunk to whole body fat(r=0.625,0.533,P<0.01).Conclusion:The expression of NPY in visceral fat of adult catch-up growing rats is significantly increased due to calorie restriction,which mediates the occurrence of catch-up fat with the increase of trunk fat content and the ratio of trunk to whole body fat in this model.